"At around 10:40 a.m. James found the suspect, Marcia Valentine, lying on their driveway," Amormino said. "He told her to leave, but instead she got into her 2004 silver Mercedes and tried to run him over three to four times. ... Valentine tried to kill him."

Bullock, 42, as well as James's 10-year-old son, Jesse Jr., witnessed the attack.

"Both Jesse James and Sandra Bullock are fine and it is now in the hands of the authorities," Bullock's rep, Cheryl Maisel, tells PEOPLE.

After the attack on James, 38, Valentine fled the scene. However, the following day, just before 10 a.m., an officer recognized her car and arrested her for assault with a deadly weapon. She has since posted $25,000 bail, and is due in court on May 22.

Valentine, 46, had stalked Bullock in the past, Amormino said. However, the sheriff's spokesman was unable to confirm whether Valentine had a previous arrest record or whether any restraining orders had been filed against her.